Small-angle neutron scattering study of sodium cholate and sodium deoxycholate interacting micelles in aqueous medium

Abstract

Small angle neutron scattering (SANS) measurements of D 2 O solutions (0⋅1 M) of sodium cholate (NaC) and sodium deoxycholate (NaDC) were carried out at T = 298 K. Under compositions very much above the critical micelle concentration (CMC), the bile salt micelle size growths were monitored by adopting Hayter-Penfold type analysis of the scattering data. NaC and NaDC solutions show presence of correlation peaks at Q = 0⋅12 and 0⋅1 Å-1 respectively. Monodisperse ellipsoids of the micelles produce best fits. For NaC and NaDC systems, aggregation number (9⋅0, 16⋅0), fraction of the free counterions per micelle (0⋅79, 0⋅62), semi-minor (8⋅0 Å) and semi-major axes (18⋅4, 31⋅7 Å) values for the micelles were deduced. Extent of micellar growth was studied using ESR correlation time measurements on a suitable probe incorporating NaC and NaDC micelles. The growth parameter (axial ratio) values were found to be 2⋅3 and 4⋅0 for NaC and NaDC systems respectively. The values agree with those of SANS.

Sodium cholate, a solubilizing agent for the necrosis avid radioiodinated hypericin in rabbits with acute myocardial infarction

“…The best results were achieved by using 0.06 M NaCh, which is in agreement with a previous study (Ji et al, 2013). This could be due to the fact that such a concentration is nearly above the secondary CMC (0.05 M) reported for sodium cholate at 25 C (O'Connor et al, 1983;Conte et al, 1984;Santhanalakshmi et al, 2001), which favors the 123 I-Hyp/Hyp solubilization. At surfactant concentration above the CMC, the formed micelles are able to accommodate the hydrophobic molecule due to an increase in micelle-bound solutes, thus improving the solubility of the molecule in the medium.…”

“…At a certain concentration (0.013-0.018 M) known as critical micellar concentration (CMC), it forms micelles that act as an encapsulating agent for dietary fats, hydrophobic substances and guarantee efficient transport and absorption of poorly water soluble nutrients. Due to the enlargement of the size of the primary micelles caused by the hydrogen bonding forces among the hydrophilic regions, a secondary micellization occurs at higher concentration of NaCh (0.05 M) (O'Connor et al, 1983;Conte et al, 1984;Santhanalakshmi et al, 2001).…”

Self-assembly in aqueous bile salt solutions

“…More recently small-angle X-ray and neutron scattering has been used, which provides information on a smaller length scale [16,[44][45][46][47][48][49]. A determination of the micellar structure on an atomic level is nevertheless impossible, since the aggregates are very mobile, highly dynamic with aggregates continuously breaking and reforming and the structure varying between individual micelles with scattering only providing averages.…”

Effect of temperature and pH on 31P nuclear magnetic resonances of phospholipids in cholate micelles

“…As a consequence of the small size of the micelles formed by these facial amphiphiles in water (Chen et al, 1992), high spectral resolution has been achieved for PL-related resonances (Pearce et al, 1993;Pearce and Komoroski, 2000;Komoroski et al, 2001;Schiller and Arnold, 2002) in the presence of these detergents. Aggregation numbers reported for primary micelles of cholate, deoxycholate, taurocholate, deoxytaurocholate are less than 20 (Santhanalakshmi et al, 2001;Hildebrand et al, 2003;Sugioka et al, 2003;Hildebrand et al, 2004). As the PLs in these mixed micelles are not clumped tightly to each other it is even possible to resolve resonances corresponding to PLs of the same class but with different acyl chain composition (Pearce et al, 1993;Pearce and Komoroski, 2000;Komoroski et al, 2001;Schiller and Arnold, 2002).…”